The Vikings' worst fears have been confirmed. Wide receiver Greg Childs' rookie season is over. His NFL career likely is in serious jeopardy as well.

On the second-to-last play of Saturday night's practice at Blakeslee Stadium, Childs took an awkward fall, screamed out in pain and left the field on a cart. On Sunday, the Vikings announced Childs had torn the patellar tendon in both of his knees, devastating injuries to a young and promising player who had battled so hard to return to health.

That gamble the Vikings took, rolling the dice and drafting Childs late in the fourth round in April? The pit boss cruelly has collected the chips.

The worries were there with Childs. His junior season at Arkansas was cut short when he suffered a torn patellar tendon in his right knee, an injury that also hindered him throughout 2011. His senior season production: averages of two catches and 22 yards per game without a touchdown.

Then, a week after being drafted, Childs suffered a calf strain during rookie minicamp, a setback that further limited him during organized team activities (OTAs) and minicamp.

All of that led coach Leslie Frazier to set a pretty straightforward agenda for Childs as training camp began.

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"You want him to be able to show that he can stay healthy," Frazier said. "That's a big deal, being available."

Yet the promise in Childs was visible, too. At 6-3 and 217 pounds, he offered a big downfield target. Childs had the size to muscle past smaller defensive backs, the speed to get open down the field and the body control and strength to make tough catches in tight coverage.

That was evident last Thursday when he delivered the most eye-opening highlight of camp so far, a 26-yard touchdown grab from Joe Webb during which he leaped over cornerback Brandon Burton, pinned the football to Burton's back, then fully controlled it as they went to the ground.

"Great concentration," Frazier said. "That's what we need. We need a guy to make that hard catch for us even when he's covered. That's good to see."

Now? After Saturday's spill, Childs faces another physically and emotionally taxing rehabilitation process -- on two knees this time, instead of just one.

That will create an incredibly steep climb for Childs to even think about returning to action in the NFL.

It will also create an immediate opening for another Vikings receiver in the preseason.

If the team plans to keep five receivers on the 53-man roster -- as is customary -- and it's assumed Percy Harvin, Jerome Simpson and Jarius Wright are locks to make it, there will now be a fierce battle among the other pass catchers in camp to show their stuff.

Veterans Michael Jenkins or Devin Aromashodu both have established rapport with second-year quarterback Christian Ponder and could each provide reasons to be kept around. But Jenkins is also 30 and due to make $2.5 million this season, and Aromashodu, now 28 and heading into his fifth NFL season, has career totals of 67 catches for 1,011 yards and five touchdowns.

Stephen Burton, drafted in the seventh round in 2011 out of West Texas A&M, has made an impression on the coaching staff and could have the biggest opportunity to step forward following Childs' exit.

Emmanuel Arceneaux and Kerry Taylor are also in the mix, with Bryan Walters and Kamar Jorden facing longer odds to make it.